90023: One of 'TemplateArgs' dictionary value is null

This error occurs when your request includes TemplateArgs and at least one dictionary value is null. Replace that entry with a real substitution value before you send the request. If you are using current content templates, Twilio also requires non-null values for ContentVariables.

• Your request payload includes a TemplateArgs key whose value is null.
• Your application maps an optional or missing field into the template argument payload, and that field is serialized as null at send time.
• You build template substitutions dynamically and do not validate the final payload before sending it. As a result, one or more values resolve to null.

• Inspect the final outbound request and identify every TemplateArgs entry before you send it. Remove any path in your application that allows a template value to resolve to null.
• Replace each null entry with a valid substitution value that matches the placeholder your template expects.
• Add application-side validation for any field you copy into template arguments, especially values loaded from forms, databases, or upstream APIs. Reject the request or supply a valid value before you create the Twilio API request.
• If you are sending a content template through the current Messaging API, send ContentSid with a valid JSON string in ContentVariables and make sure each variable value is non-null. If your template defines default variable values, use those defaults instead of sending null.

• Using Variables with Content Templates
• Send templates created with the Content Template Builder
• Messages resource